A study to be published Tuesday in The Archives of Internal Medicine suggests that several cancers can disappear on their own, without treatment being necessary, after on odd occasions in the past, some melanomas and kidney cancers were reported to have gone away on their own.

Nevertheless, now researchers have revealed that the tumors that simply vanish without the patient receiving cancer treatment are in a larger number, and not just casual instances.

Recently, in Norway, scientists reported a breast cancer case in which the tumor disappeared on its own, which left them wondering about how many invasive cancers could actually vanish without medical interference.

The new study was conducted by researcher at the VA Outcomes Group in White River Junction, Vermont and Dartmouth Medical School Dr. H. Gilbert Welch, along with Dr. Per-Henrik Zahl of the Norwegian Institute of Public Health and Dr. Jan Maehlen of Ulleval University Hospital in Oslo.

Researchers monitored two groups of women aged 50 to 64 over two consecutive periods of six years. The first group, comprising 109,784 women, underwent monitoring between the years 1992 and 1997, while the second one, consisting of 119,472 women, was followed from 1996 to 2001. Beginning 1996, all the women were offered mammograms, and nearly all of them accepted to undergo this mainstay breast cancer diagnosing procedure.

Scientists found that for every 100,000 women who had undergone regular screenings, 1,909 were diagnosed with breast cancer during the six year monitoring period, compared to 1,564 women who had not been routinely screened on a regular basis.

Drawing on these results, researchers concluded that the women in the latter group had developed cancer at some point, but the tumor had disappeared on its own.

Nevertheless, this should by no means render women to stop having their breasts regularly scanned in order to detect any lumps that might lead to cancer in due time and timely undergo necessary treatment.